Power tool system

1. A battery pack system, comprising: a first battery pack, comprising a plurality of battery cells capable of providing a first voltage and a second voltage and a tool interface configured to mate with a first tool having a rated voltage equal to the first voltage and a second tool having a rated voltage equal to the second voltage; and a second battery pack, comprising a plurality of battery cells capable of providing only the first voltage and a tool interface configured to mate with the first tool and not mate with the second tool; wherein the first and second battery packs comprise a mechanical tool lockout to allow the first battery pack to mate with the second tool and to prevent the second battery pack from mating with the second tool; and wherein the mechanical tool lockout comprises a slot at a location on the first battery pack for receiving a protrusion on the second tool and a solid portion at a location on the second battery pack corresponding to the location on the first battery pack to prevent receiving the protrusion on the second tool.

2. The battery pack system, as recited in claim 1 , further comprising a battery charger comprising a battery pack interface configured to mate with the first battery pack tool interface and the second battery pack tool interface and charge the first battery pack and the second battery pack at the first voltage.

3. The battery pack system, as recited in claim 1 , wherein the second voltage is a whole number multiple of the first voltage.

4. A battery pack system, comprising: a first battery pack comprising a first plurality of battery cells and configured to provide only a first operating voltage; and a second battery pack comprising a second plurality of battery cells and configured to provide the first operating voltage and a second operating voltage that is different from the first operating voltage; the first battery pack configured to mechanically and electrically couple with a first power tool such that the first battery pack provides the first operating voltage to the first power tool; and the second battery pack configured to mechanically and electrically couple with the first power tool such that the second battery pack provides the first operating voltage to the first power tool and to mechanically and electrically couple with a second power tool such that the second battery pack provides the second operating voltage to the second power tool; wherein the first and second battery packs comprise a mechanical tool lockout to allow the second battery pack to mate with the first power tool and the second power tool and to prevent the first battery pack from mating with the second power tool; and wherein the mechanical tool lockout comprises a slot at a location on the second battery pack for receiving a protrusion on the second tool and a solid portion at a location on the first battery pack corresponding to the location on the second battery pack to prevent receiving the protrusion on the second tool.

5. The battery pack system, as recited in claim 4 , further comprising a battery charger configured to electrically and mechanically mate with the first battery pack and the second battery pack and charge the first battery pack and the second battery pack at the first voltage.

6. The battery pack system, as recited in claim 4 , wherein the second operating voltage is a whole number multiple of the first operating voltage.